Atmospheric-river-induced foehn events drain glaciers on Novaya Zemlya

Recently, climate extremes have been grabbing attention as important drivers of environmental change. Here, we assemble an observational inventory of energy and mass fluxes to quantify the ice loss from glaciers on the Russian High Arctic archipelago of Novaya Zemlya. Satellite altimetry reveals that 70 ± 19% of the 149 ± 29 Gt mass loss between 2011 and 2022 occurred in just four high-melt years. We find that 71 ± 3% of the melt, including the top melt cases, are driven by extreme energy imports from atmospheric rivers. The majority of ice loss occurs on leeward slopes due to foehn winds. 45 of the 54 high-melt days (>1 Gt d−1) in 1990 to 2022 show a combination of atmospheric rivers and foehn winds. Therefore, the frequency and intensity of atmospheric rivers demand accurate representation for reliable future glacier melt projections for the Russian High Arctic.

) as used in Table S2.

Fig. S4 :
Fig. S4: Comparison of yearly area-specific mass changes of marine-and land-terminating glaciers.Those years that were mentioned in the main article can be identified using the legend; other years are colored in blue.

Fig. S5 :
Fig. S5: June and September MAR SMB including averages for the periods 1981-2010 and 2011-2022.The dotted line shows the modeled values for each year and the solid line the low-pass filtered version thereof.The dashed lines and shaded areas show the averages and their 2σ-confidence intervals for the periods 1981 to 2010 and 2011 to 2022.

Fig. S6 :
Fig. S6: Daily MAR melt in 2016.Dashed line represents the low-pass filtered version (gaussian window, σ = 31 days).Orange areas highlight the daily melt above its low-pass filtered version.

Fig. S7 :
Fig. S7: Melt above its low-pass filtered version (cmp.orange highlighted areas in Fig. S6).Dotted lines show raw data, solid lines show a low-pass filtered version, dashed lines indicate the averages from 1981 to 2010 and 2011 to 2022, and the shaded areas indicate the 2σ-uncertainty intervals of the averages.

Fig. S9 :
Fig. S9: In analogy to main article Fig. 4, this figure shows the average conditions at 12 UTC for 12 days with westerly winds and MAR melt exceeding 1 Gt (see Table S3).The panels show the CARRA (a) air temperature, (b) vertical air velocity, (c) relative humidity, and (d) cloud liquid water content along the transect highlighted in panel (e) from west to east.In panels (a-d), the brown and blue colored shapes indicate land and glacierized areas, respectively.The contourlines in panel (b) show isotherms of the potential irreversible moist-adiabatic temperature in • C. Panel (e) shows the average CARRA wind speeds at 850 hPa, the average MAR melt, and the coastline of Novaya Zemlya.

Fig. S11 :
Fig. S11: Comparison of number of days per year with an AR 2 closer than 50 km or moist conditions (see main article).

Fig. S13 :
Fig. S13: Comparison of yearly melt-season average from MAR and MODIS.The thin black dashed line indicates the identity line.

Fig. S14 :
Fig. S14: The panels show average CARRA (a) air temperature, (b) vertical air (c) relative humidity, and (d) cloud liquid water content on 22 July, 1996, along the transect highlighted in the unlabeled bottom panel from west to east.In panels (a-d), the brown and blue colored shapes indicate land and glacierized areas, respectively, and the contourlines show isotherms of the potential irreversible moist-adiabatic temperature in K.The bottom panel shows the average CARRA wind speeds at 850 hPa, the average MAR melt, and the coastline of Novaya Zemlya.
List of dates in 1990-2022 with more than 1 Gt surface melt water production according to MAR.For each day we indicate whether we find foehn winds based on transects of daily average air temperature, wind speeds, and humidity from CARRA.Further, we indicate the wind direction by "E", "W", or "other" for easterlies, westerlies, or other wind directions, respectively (see Methods in main article).